Sanding them sounds like a really good idea, but let me tell you it is not.
I learned the hard way about aluminum. My dad had a horse trailor that was aluminum, it was really starting to look crappy, it was really dull and dirty looking so we sandblasted it. Hey we had a nice shiny trailor but after the first couple of trips it looked the exact same. The oxidation on aluminum protects the rest of it from oxidizing. So if you sand it you only get the good look for a few weeks and then you are in the same situation.